Researchers have found evidence of higher risk for autism among boys. / mizina, stock.adobe.com
Heidelberg – Autism occurs 4 times more often in boys than in girls. For the first time in the Heidelberg University Hospital, scientists from the molecular genetic genetics found an explanation: their studies of human cells and mouse brain regions showed that male sex hormone testosterone actively activates certain brain risk genes before and after birth. The results were Boundaries in the Neuroscience of the Molecule published (2018; doi: 10,3389 / fnmol 2018,00337).
To date, it has only been known that deficiencies in these genes are a strong risk factor for the development of neuronal developmental disorders. New findings suggest that these genetic defects may have a greater impact on men's brain than female individuals.
"Now, we have the first indication that – at least in relation to numerous risk genes – the boys have a significantly higher risk of autism than girls," says Gudrun Rappold, MD, Director of Molecular Genetics.
Testing for his group showed that young genes in male mice, known as SHANK 1, 2, and 3, are increasingly becoming proteins and have higher hormone hormone testosterone values. The Heidelberg research team has been investigating SHANK genes for many years, as deficiencies in genetic information have an important role in the development of autism and other mental health disorders.
Add testosterone – more stem protein
In the tests, the team used the cell culture of the childhood brain tumor (neuroblastoma) as a model for the development of neurons. Researchers found in these cells that the activation of SHANK genes depends on the binding of testosterone to the androgen receptor. When this receptor was blocked, the strong activation of the risk genes disappeared. "We have been able to confirm this in brain areas in young mice in which this androgen receptor was not formed: they were significantly less active than in controlled animals with intact receptors," says Simone Berkel, this study conducted with a graduate student Ahmed Eltokh.
Researchers also investigated the amount of protein in the stem in the young male and female mice before and after birth. Male animals with naturally more testosterone in the blood and the brain found significantly larger Shank proteins than women. "We believe that a greater number of arm proteins in the man's brain will increase the" perforation "of the errors in the SHANK genes and thus lead to higher autism risk," says Rappold.
In autism, the development of neurons in the brain is disturbed. One is 68 children (about 1.5%). Typical symptoms are noticeable early, so the diagnosis is usually done before the 3rd year of life. Autistic people have difficulties in social interaction, communication and observation, and often have intense, special interests and abilities, as well as recurring and narrow (restrictive) behavioral patterns. However, these characteristics of autistic behavior may vary greatly from patient to patient – one therefore speaks of autism spectrum. © IDW / energy / aerzteblatt.de